On Wed, Apr 13, 2005 at 01:51:44PM +0000, Jason Stover wrote:
> * test/expressions/randist.sh bails out on the beta and F distribution
> tests, but as per previous discussions, I think this is a problem
> with the test rather than the code. I'll leave it to the numerical
> analysts to work out what's going on.
I could not reproduce this problem with a recent checkout. I used a
slightly modified version of randist.sh, as well as the usual
randist.sh. The modified randist.sh is pasted below. Running diff -b
-B by hand returned no difference between the files written by
randist.sh and the files in tests/expressions/randist/.
OK. I dug a bit deeper, and it seems that I had been testing against
an older version of tests/expressions/randist/{beta,f}.out (I don't
know why cvs update didn't do its job).
But anyway, if one does:
cvs diff -r 1.1 -r 1.2 tests/expressions/randist/f.out
Then we get:
< .99 5.00 10.00 5.64 .99 .01
---
> .99 5.00 10.00 10.00 1.00 .00
I don't know why this change was made, but 10.00 is definitely wrong.
The correct answer is indeed 5.64
Similar changes to beta.out occured at the same time. I don't know if
those changes are correct or not, because I don't have a book of
tables for the beta distribution.
I think I mentioned this before, but the idf of the F dist at 0.99
with 5;10 degrees of freedom is not an extreme case, and 10.00 when
the answer should be 5.6 is a very large error.
So it seems that an error has crept in, and we've fudged the test to
fit the broken results.
J'
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